DE102009021448B3 - Device for peripheral processing of workpieces, comprises an optical system having an optical axis that emits a beam bundle along the optical axis, and/or a peripheral mirror system axis that has a workpiece axis around the workpiece - Google Patents

Abstract

The device comprises an optical system having an optical axis (15) that emits a beam bundle (3) along the optical axis, and/or a peripheral mirror system axis (9) that has a workpiece axis around a workpiece (8) to be processed. The peripheral mirror system axis and the workpiece axis are aligned in same direction. The peripheral mirror has a beam inlet opening at the peripheral to which the optical system is arranged so that the beam bundle is coupled with the optical axis vertical to the peripheral mirror system axis in the peripheral mirror. The device comprises an optical system having an optical axis (15) that emits a beam bundle (3) along the optical axis, and/or a peripheral mirror system axis (9) that has a workpiece axis around a workpiece (8) to be processed. The peripheral mirror system axis and the workpiece axis are aligned in same direction. The peripheral mirror has a beam inlet opening at the peripheral to which the optical system is arranged so that the beam bundle is coupled with the optical axis vertical to the peripheral mirror system axis in the peripheral mirror and impinges on the workpiece at the peripheral mirror (5) after several reflexion. The peripheral mirror is surrounded by a processing chamber that has a beam inlet opening and/or two discharge openings through which the workpiece to be processed is guided in the direction of its workpiece axis through the processing chamber. The optical system comprises a first beam formation optic for diameter variation and parallelization of the beam bundle emitted by laser. The optical system comprises two beam formation optics for focusing the beam bundle in X-Y plain, where the vertical plain is Y-Z plain defined to the peripheral mirror system axis through the optical axis. The two beam formation optics are laid out so that a focus line lies in a beam inlet opening. The peripheral mirror has the form of a hollow body, whose interior cover area forms a mirror surface, whose surface normal stands in each point of the mirror surface vertically on the peripheral mirror system axis. The surface normal of the mirror surface has an angle of less than 90[deg] , with the peripheral mirror system axis. The mirror surface consists of part areas that include corners, whose number, geometry and arrangement are determined to each other for the cross-section of the peripheral mirror. The mirror surface is a cone cylindrical surface. Polygons with same edge length and same interior angles are formed through the part areas. An additional mirror element is arranged in the interior of the peripheral mirror and is a rotating polygon mirror. The workpiece axis is arranged in the peripheral mirror system axis. A corner or a part area is formed as spherical or aspherical area. An additional beam inlet openings and a second optical system are provided to couple two beam bundles in the peripheral mirror. The second optical system comprises a laser that emits a beam bundle with another wavelength as the laser of the first optical system. A movement arrangement is arranged to produce a relative movement between the optical system, the peripheral mirror and the workpiece in the direction of the workpiece axis. An independent claim is included for a method for peripheral processing of workpieces by laser.

Description

The invention relates to a device for the circumferential machining of a workpiece, in particular a material strand by means of a laser, as generically from the US 3,865,564 is known. The invention also relates to a generic method that can be carried out with it.

The Invention is advantageously applicable to processes where viscous Fluid streams, z. Example of glass, polymers, organic glass, metal or the like Substances, contactless restricted or divided into portions.

The Invention is also applicable to solid stranded workpieces and Semi-finished products to separate, edit and their material properties to influence along its circumference.

It is known, strands of material mechanically working from said materials, wherein but disadvantages due to change of the properties in the editing area. So leads z. For example, the use of mechanical shears to change the material structure in Area of the cut, such. B. densifications in metallic Materials, or to local refrigerations viscous melts or fluids.

contactless Methods for processing materials reduce such adverse property changes or even lift them altogether on. In addition to the application of electrical or electromagnetic phenomena introduces the use of high energy radiation, such as lasers is emitted, a versatile applicable material processing represents.

The Use of laser radiation causes the energy of laser radiation very precise is applied to the areas of the material to be processed. Only so can the desired effects, such as As melting, separation or curing can be achieved. Farther is it for a number of applications needed the material over a defined area both evenly and simultaneously with The laser radiation to impose unwanted local thermal To avoid tension.

at the processing of rope-shaped Materials have special requirements for the technical and technological execution the laser processing. Is the material to be edited after or separated from the strand by the application of the laser radiation, can the laser together with the possibly necessary optical elements in the same axis are arranged, in which the strand-like material is moved (main axis). Remains the processed portion of the material However, on the strand, as it is z. B. in the production of fibers happens, so must the laser and at least part of the associated optical Elements are moved out of the axis of the strand-like material. Nevertheless, a precise, uniform and simultaneous loading of the workpiece over the circumference with the laser radiation guaranteed become.

Around to meet these requirements are a set of solutions known.

The DE 10 2004 003 696 A1 discloses an annular array of a plurality of lasers in a plane whose optical axes are oriented in the radial direction perpendicular to the major axis of the strand material. In the intersecting regions of the diverging laser beams, a region with a constant energy density is formed, which allows processing of the strand-like material along its circumference.

The DE 100 20 327 A1 describes how using in turn several lasers, a machining over the entire circumference of a workpiece is possible. The beams of the lasers are brought together by means of an annular optical element in an annular focus. This device is particularly suitable for machining rotationally symmetrical workpieces. The annular focus can also be generated by beam-forming optical elements of only one laser beam.

In the US 4,044,936 a device is shown, by means of which it is possible using a laser beam to edit tubular hollow body. In this case, the laser beam is selectively focused by means of optical elements on the inner or outer surface of the workpiece or material. A continuous processing of the circumferential line can be achieved by the rotation of certain, located in the beam path optical elements. An arrangement of the laser outside the major axis of the workpiece or material is described in two embodiments. The laser beam is deflected by at least one mirror and optionally focused by other optical elements. The admission is still only selective.

A technical solution for machining asymmetrical surfaces of workpieces by means of a laser is used in the US 4,456,811 specified. With the help of segmented mirrors, an annular laser beam is split up into individual partial beams and directed onto the surface of a material or workpiece to be machined. As a result, the simultaneous processing along a circumference is also possible here. The goal of this solution is to create a defined order Conversion of the energy of the laser beam in the field of application to effect. The main axis of the laser beam lies in the same axis as the main axis of the material or workpiece. Furthermore, the coupling of the laser beam emitted by a laterally offset laser beam into the main axis of the material or workpiece is disclosed by means of a perforated mirror. However, it can come to a C-shaped expression of the surface to be machined acting jet. This uneven distribution of the radiation energy must be compensated by rotation of the material or workpiece.

In the US 3,865,564 a device for the production of glass fibers by heating a glass strand is shown as starting material. The laser beam emitted by a laser located outside the main axis is shaped into an annular beam by means of a rotating, eccentrically arranged lens and directed in the direction of the main axis of the glass strand via a perforated mirror, through the opening of which the finished glass fiber is guided. Via a conical mirror whose axis coincides with the main axis of the glass strand and which comprises the glass strand to be processed completely and symmetrically, the laser beams are directed onto the surface of the glass strand. The glass strand is heated by the impingement and can be pulled into a fiber. In the region of the conical mirror, therefore, the laser beams coming from the laser source and deflected by the perforated mirror are uniformly distributed over a defined width of the circumference of the glass strand and an area of uniform energy distribution is created.

The in the US 3,865,564 The disclosed arrangement and mode of action of the individual elements enables uniform application of a strand-shaped and potentially infinitely long material or workpiece in a defined area over its entire circumference with laser radiation. A simple workpiece feed and the processing of hot workpieces is counteracting said hole mirror.

Also is the entire device on the workpiece to be machined, here a fiber, dimensioned out. For machining workpieces with a much larger diameter the entire device must be adapted in its dimensioning.

From the US 4,012,213 For example, a method of making refractory fibers that are drawn from a rod-shaped material is known. The rod-shaped material is moved at a predetermined speed through a heating zone. To create the heating zone there are means for emitting laser radiation and optical means for dividing the laser radiation into a plurality of laser beams, as well as for deflecting and focusing these laser beams on the circumference of the rod-shaped material. There is no homogeneous loading of the circumference of the material with laser radiation.

Also according to the US 4,058,699 Laser heating creates a heating zone in a heating device. Within a cylindrical peripheral mirror having an elliptical cross-section, a conical reflector is arranged along a first cylinder axis extending through the first focal point of the elliptical cross section, and a rod-shaped workpiece to be heated is guided along a second cylinder axis passing through the second focal point of the elliptical cross section. On the conical reflector an expanded laser radiation is directed, which strikes after multiple reflections from all sides on the circumference of the workpiece. The laser radiation is coupled parallel to the axis of the workpiece in the heater, so here in the axial direction a suitable space must be available. Moreover, due to the elliptical cross-sectional shape of the peripheral mirror, this device is subject to restrictions for the coupling of the laser radiation and for the arrangement of the workpiece within the peripheral mirror.

adversely at the previous solutions are their high complexity, Among other things, in the simultaneous arrangement of several Laser or in the use of rotating optical elements shows. These measures serve on the one hand the energy conversion at the place of processing and for others the coupling of one of a laterally arranged laser emitted laser beam. A machining of asymmetrical workpieces requires a reglung technically complex readjustment of the laser processing system. So far, there is also a lack of a solution in the event that that too machining workpiece not in the middle of the arrangement for laser processing.

Of the Invention is based on the object, a compact device to find, which allows a simple feed of a workpiece and with only a few changes to the machining of workpieces different cross-section and different dimension is customizable.

It It is also an object of the invention to provide an alternative method of processing the circumference of a workpiece to find by means of laser, wherein a loading of the workpiece with a given energy distribution over the circumference be possible should.

These The object is achieved by a device having the features of the claim 1 and for a method with the features of claim 20 solved. advantageous Further developments are each described in the subclaims.

Based In the drawing, the apparatus and method will be described below example closer explained.

It demonstrate:

1 a schematic diagram of a device according to the invention

2a the course of a beam in the YZ plane to the first reflection

2 B the course of a beam in the XY plane to the first reflection

3a the course of a beam in a perimeter mirror 5 formed by a circular cylindrical mirror in a workpiece with a smaller workpiece radius

3b the course of a beam in a perimeter mirror 5 formed by a circular cylindrical mirror in a workpiece with a larger workpiece radius

4 a circumferential mirror 5 formed by a cuboid mirror with a square cross-section

5 a circumferential mirror 5 formed by a prismatic mirror with a 5-corner as a cross section and additional mirror elements 14

6 a circumferential mirror 5 formed by a prismatic mirror with an 8-corner as a cross section and additional mirror elements 14

7 a circumferential mirror 5 with a polygon mirror as additional mirror element 14

8th a circumferential mirror 5 with an angle mirror as an additional mirror element 14

9 a device with an additional optical system and two jet entry openings

10 a circumferential mirror 5 formed by a circular frustoconical or truncated pyramidal mirror with round or n-shaped cross-sectional area

11 a partial circumference machining of a workpiece 8th

12 a model for the course of rays of the beam 3 within a circumferential mirror 5

13 a diagram for the energy distribution over the circumference of a workpiece 8th An inventive device, shown in principle in 1 , includes a processing chamber 13 and an optical system having an optical axis 15 , which by a laser 1 and basically a first beam shaping optics 2 for changing the diameter and parallelizing one of the lasers 1 emitted beam 3 and a second beam shaping optics 4 for focusing the beam 3 is formed in an axial direction. The processing chamber 13 has lead-through openings 7 on, through which a workpiece to be machined 8th in the direction of its workpiece axis 11 (referred to in the art as the main axis) is guided.

The processing chamber 13 encloses a peripheral mirror 5 with a peripheral mirror system axis 9 , The workpiece axis 11 and the peripheral mirror system axis 9 are aligned parallel to each other or preferably coincide. The processing chamber 13 and the peripheral mirror 5 each have an identical beam entry opening 6 to which the optical system is arranged so that the beam 3 with the optical axis 15 perpendicular to the peripheral mirror system axis 9 in the peripheral mirror 5 is coupled and after multiple reflection on the peripheral mirror 5 on the workpiece 8th incident.

Depending on the geometry of the workpiece 8th and the processing target, the device advantageously has at least one movement device which is suitable for a relative movement between the optical system and the peripheral mirror 5 and the workpiece 8th to create.

Such relative movement is necessary when the workpiece 8th not just to be separated or edited in a length equal to the width of the work area 10 corresponds, but is to be processed over long lengths or its total length partially or completely on the circumference.

In the case of strand-shaped workpieces, the workpiece is advantageous 8th along its workpiece axis 11 emotional. A rotation around its own workpiece axis 11 can be used to influence the energy input over the circumference.

For workpieces 8th , one after the other, individually for processing in the peripheral mirror 5 can be introduced, it may be beneficial to the tool, ie the beam 3 to move, which in particular by the movement of the entire optical System with or without the peripheral mirror 5 in the direction of the workpiece axis 11 is beneficial. Will the circumference mirror 5 not moved, must the jet entrance opening 6 be designed as a correspondingly long slot, so that the beam 3 can be coupled over the entire intended range of motion. After completion of a workpiece 8th can the optical system be moved back to its original position or with the return movement is already the subsequent workpiece 8th processed.

For example, for the mere separation of a strand-shaped workpiece 8th it is advantageous if at least one movement device is present which is suitable, the optical system, the peripheral mirror 5 and the workpiece 8th during machining together in the direction of the workpiece axis 11 to move. Thus there is no relative movement, which also with a longer duration of the jet effect and high feed rate of the workpiece 8th the workpiece over a length equal to the width of the work area 10 is processed. After each machining operation, the optical system and, if moved, also the peripheral mirror 5 moved back to their original position.

Instead of a moving unit for the optical system, moving, optically deflecting elements, which are the optical axis, can also be provided within the optical system 15 in the peripheral mirror 5 incident beam 3 a given movement of the workpiece 8th track temporarily.

To carry out the method is a peripheral mirror 5 with a peripheral mirror system axis 9 provided in which a workpiece 8th with a workpiece axis 11 is introduced so that the circumferential mirror system axis 9 and the workpiece axis 11 in one direction.

Over a given processing time becomes a beam 3 along an optical axis 15 perpendicular to the peripheral mirror system axis 9 extending into the peripheral mirror 5 coupled and reflected at the mirror surface several times until it hits the workpiece 8th incident.

As a laser 1 All types of lasers applicable in materials processing, such as CO ₂ lasers, NdYAG lasers, in rod-shaped or disc-shaped arrangements, fiber lasers or high-power diode lasers, are suitable both as continuously emitting lasers, pulsed lasers or oscillator amplifier arrangements. The selection and adjustment of the laser and process parameters depends on the material properties of the workpiece 8th and the processing target. For the understanding of the invention is intended by the laser 1 emitted radiation as a beam 3 be understood, which over the duration of the processing time of the laser 1 is sent out.

Depending on the emission characteristics of the laser 1 is the first beam shaping optics 2 z. As a collimator, a telescope or DEO (diffractive optical element) to a quasi axis-parallel over the beam path bundle 3 to form, ie a bundle of rays 3 with minimal divergence at a sufficient for the processing target high energy density, or around the beam 3 so as to change in diameter, in particular, to widen that to a desired width for a working area 10 passing through the diameter of the beam 3 in the XY plane is reached. Unless the selected laser 1 already emitted with a sufficiently small divergence angle, ie the deviation from an axis parallelism can be tolerated, is this first beam-shaping optical system 2 not mandatory.

The second beam shaping optics 4 is preferably a cylindrical lens, which the beam 3 in the direction perpendicular to the cylinder axis, in the direction of the peripheral mirror system axis 9 runs, focused.

Based on a Cartesian coordinate system, by its coordinate origin, the optical axis 15 runs, becomes the beam 3 focused in the XY plane so that a focus line is created in the YZ plane.

In the direction of the cylinder axis, ie in the YZ plane, the beam remains 3 unaffected and has over the entire beam path to a quasi-constant width, the width of the irradiated area (working area 10 ) is determinative. In the case of the coupling of a parallel beam 3 in the peripheral mirror 5 eliminates this second beam shaping optics 4 ,

In the 2a and 2 B is the course of a ray bundle 3 in the two mentioned, excellent levels by the second beam shaping optics 4 , formed by a cylindrical lens, up to the first reflection in the peripheral mirror 5 shown.

Advantageous is the optical arrangement formed by the laser 1 and the two beam shaping optics 2 . 4 , so dimensioned and to the beam entry opening 6 arranged that in the beam 3 training focus line in the beam entrance opening 6 lies. This can be done very narrow, which is the risk of re-emergence of shares once in the peripheral mirror 5 coupled beam 3 reduced to a minimum. The jet entrance opening 6 can be a true opening in the editing kam mer 13 and the peripheral mirror 5 be, or else an area where the processing chamber 13 and the peripheral mirror 5 for the beam 3 the laser 1 are transparent. In the most practical embodiment, the jet inlet opening 6 in the processing chamber 13 formed as a window and in the peripheral mirror 5 is the jet entrance opening 6 a true opening.

The circumference mirror 5 is formed by the inner circumferential surface of a cylindrical, cuboid or prismatic hollow body or in special embodiments of a hollow truncated cone or Hohlpyramidenstumpfes. In this case, the inner lateral surface form a mirror surface, which is composed of a plurality of partial surfaces, their number, geometry and arrangement to each other for different, possible cross-sections of the peripheral mirror 5 is determinative, as will be explained in more detail in the following embodiments.

For the function of the peripheral mirror 5 only the mirror surface is decisive, ie if the peripheral mirror 5 , as in 1 shown from a processing chamber 13 is surrounded, this serves only to receive the peripheral mirror 5 and the enclosure of the coupled-in beam 3 , The enclosure is therefore a safety measure and is not essential for the functioning of the device.

The different suitable cross sections of the peripheral mirror 5 are dependent on the cross section of the workpiece 8th and the processing goal advantageous.

As cross sections for the peripheral mirror 5 In particular, a circle, an oval and polygons formed by partial surfaces come into consideration with preferably identical edge lengths and identical internal angles for manufacturing reasons.

Additional mirror elements 14 as in the 5 and 6 shown in the interior of the perimeter mirror 5 are free or arranged on this, the targeted guidance of the beam 3 support.

It is the goal, the temporally limited coupled bundle of rays 3 so within the perimeter 5 By reflection, it ultimately leads to the circumference of the workpiece 8th and its radiant energy is absorbed at the point of impact. With the impact of the beam 3 on the workpiece 8th has the beam 3 , starting from the laser 1 , covered his ray path. At the location of the absorption material is influenced. In the case of a material removal the way for the beam is 3 released so that subsequent radiant energy on the workpiece 8th is passed and after further reflection of the beam 3 on the peripheral mirror 5 elsewhere on the circumference of the workpiece 8th incident.

Ideally, the circumferential mirror 5 and any additional mirror elements 14 on the circumferential geometry and dimension of the workpiece 8th tuned so that the peripheral surface or a peripheral surface of the workpiece 8th if only this is to be edited, within the work area 10 is applied uniformly with radiant energy.

A device according to the invention is particularly suitable for circumferential machining of cylindrical, wire-shaped, band-shaped or tubular workpieces 8th , in particular long or so-called endless strand materials. The endless strand materials are defined by the perimeter mirror 5 in the direction of its peripheral mirror system axis 9 guided so as to be processed over their entire length or even in sections over their length. Because of the circumferential mirror 5 in the direction of the peripheral mirror system axis 9 is freely accessible on both sides, is a supply, implementation and discharge of the workpiece 8th simply possible, ie handling equipment necessary for this have free access. Under long strand materials and individual parts such as screws, bolts and pipe sections are to be understood.

It is also advantageous that by exchanging only the peripheral mirror 5 or the processing chamber 13 with the handling mirror 5 the device to workpieces 8th other cross-sectional geometry or other dimensioning or can be adapted to another processing target.

That the processing chamber 13 can be connected to a suction device to dissipate the detached material by the laser beam, the skilled person is known. Also can be a cooling for the perimeter mirror 5 be provided.

Basically, the workpiece axis 11 in the circumferential mirror system axis 9 However, in special performance examples, it can also be arranged in parallel for this purpose.

In any case, the workpiece axis 11 and the peripheral mirror system axis 9 aligned in the same direction.

The workpieces 8th In particular, viscous fluid strands can also be used instead of solid strands, for which contactless processing in the manner according to the invention is of particular advantage.

Under processing or the processing target should be understood here any conceivable material influencing by means of laser radiation, such. As a heating, evaporation and sublimation, erosion, irradiation for surface modification, coating and narrowing or separation of the material strand. For the selection of a suitable circumferential mirror 5 with its geometry and its sizing is in particular to distinguish whether the workpiece 8th should be completely severed, including the work area 10 is to be made as narrow as possible, or whether over a peripheral area a surface removal or a surface thermal influence of the workpiece 8th should be done, including the work area 10 have a predetermined width or should be as wide as possible.

It can have a workspace 10 the entire circumference or just a portion of the circumference of the workpiece 8th be edited, for. B. by heating only the underside of a steel strip.

The workpieces 8th can consist of any laser-processable materials, such as. As glass, polymers and metals and their melts.

The workpiece 8th , in particular a strand of material, can during the processing to the peripheral mirror 5 in the direction of its workpiece axis 11 are relatively moved and / or around its workpiece axis 11 be turned or remain in peace. So that the workpiece 8th It can be moved at a constant speed, it is particularly advantageous for increasing the local energy input, if a movement device is provided, with which the optical system during machining the workpiece 8th is tracked.

If and what kind of relative movement and at what speed if necessary, depends from the processing target.

Instead of just one optical system, the device may also include two or more optical systems, each with lasers 1 are equipped, the beams 3 emit different wavelengths.

A simultaneous or temporally successive treatment with bundles of rays 3 different wavelength can z. B. be advantageous if workpieces 8th be machined from a semi-transparent material that absorb different wavelengths differently in different depths of processing.

The z. B. two optical systems can each have a beam entrance opening 6 be assigned, bringing a superposition of workspaces 10 is possible, or the bundles of rays 3 be offset from each other in the coupling height, through a common beam entry opening 6 coupled accordingly in the direction of the circumferential mirror system axis 9 is extended, so that a temporal sequential processing can take place.

Below are some embodiments are shown, in particular by different embodiments of the peripheral mirror 5 differ.

In a first embodiment, explained to the 3a and 3b , the circumferential mirror becomes 5 formed by a circular cylindrical mirror, which is represented by the mirror surface as a circular line with a radius of curvature R _SP .

The drawing plane represents the XY plane in which the ray bundle 3 as a divergent beam propagates through multiple reflections at the curved with the radius R _SP mirror surface.

From that in the peripheral mirror 5 incident beam 3 are a Achsstrahl by a thin dash line 3.1 , by a thick solid line a first marginal ray 3.2 and by a thick dash line the second edge beam 3.3 shown.

All rays of the beam 3 intersect in the focus line, which is in the beam entrance opening 6 lies, with the marginal rays 3.2 . 3.3 with the axis beam 3.1 half the opening angle α with each other, which is responsible for the divergence of the beam 3 determining and the axis beam 3.1 with a surface normal passing through the focus line 12 the mirror surface includes an inclination angle β, which is the direction of incidence of the beam 3 in the peripheral mirror 5 is determinative.

As with a comparison of 3a and 3b is clearly recognizable, runs the multi-reflected edge beam 3.2 with the same parameters α, β and R _SP always tangential to a central region with the limiting radius R. All other rays of the beam 3 , here are only the first marginal ray 3.2 and the second marginal ray 3.3 shown, run at a greater distance to this central area.

While, as in 3a shown a workpiece 8th with a radius R _w smaller than R _i not through a beam 3 is taken and thus no material processing takes place, a workpiece 8th with a radius R _w , which is greater than R _i , are machined over a certain depth of the workpiece circumference, starting over its circumference.

The first embodiment for a order fang mirror 5 is advantageous suitable z. B. for removing or curing surface layers, in particular rotationally symmetric strands of material, where the workpiece 8th only to be influenced to a given depth.

About the selection of the parameters α, β and the width of the beam 3 in YZ-level becomes the workspace 10 in its width over the circumference of the workpiece 8th and its depth, into which the workpiece 8th from its circumference, starting from the impingement of the beam 3 with radiation energy is applied, given.

The depth results here from the difference of the workpiece radius R _w and the adjusting itself by the selected beam parameters limit radius R _i , which z. B. a groove of predetermined depth and width on the workpiece 8th can be produced.

When half the opening angle α and the inclination angle β are controlled so that the boundary radius R _i at the start of machining is equal to the workpiece radius R _w and reaches zero after a predetermined time regimen, the workpiece becomes 8th according targeted and reproducible acted upon by radiation energy. Is the material of the workpiece 8th for the laser wavelength of the radiation beam 3 Semitransparent, so can the radiant energy in the workpiece 8th penetration.

Especially it comes with viscous materials with strong dependence the viscosity from the temperature, such as. B. in a molten glass, for simultaneous Heat, Reducing the viscosity, evaporation, Narrowing due to the effect of surface tension and separation or dripping due to the action of gravity or other external forces.

The workpiece 8th can during the processing in relative calm to the peripheral mirror 5 and thus to the spreading beam 3 be or along its workpiece axis 11 be moved, which in correlation with the axial velocity, a planar irradiation over a width greater than the working area 10 he follows.

While editing, the entire workspace remains 10 radiation-filled and the workpiece 8th is uniformly irradiated or processed simultaneously over its circumference.

In a second embodiment, explained with reference to 4 , the circumferential mirror becomes 5 formed by a mirror with a square cross-section, ie the mirror surface consists of four planar faces that form right angles with each other.

Shown are starting from the beam entry opening 6 in which the focus line of a ray bundle 3 lies, an axle jet 3.1 and the marginal rays 3.2 and 3.3 of the beam 3 , which are provided in sections according to the previous reflections with an exponent.

This allows the beam guidance within the peripheral mirror 5 follow well and shows z. B. a first impact of the beam 3 through the marginal ray 3.2 ⁴ on the workpiece 8th after the fourth reflection.

In comparison with the first embodiment for a peripheral mirror 5 , it is advantageous in this solution, if the workpiece 8th during its machining around its workpiece axis 11 is rotated, whereby the material influence is homogenized over the circumference.

Favorable Homogenization also affects the adaptation of the number of subareas off and a reflection in the corners between the faces that causes a beam splitting.

In 5 is a third embodiment of a peripheral mirror 5 shown, which is formed by a mirror with a 5-sided cross-section.

A ray of light 3 which, as in the preceding embodiments, in the jet entry opening 6 forms a focus line, diverges in the drawing plane representing the XY plane. The ray bundle 3 represented by the three rays 3.1 . 3.2 and 3.3 , so in the circumferential mirror 5 coupled, that it impinges on a concave formed between two adjacent faces corner, whereby the beam 3 is greatly fanned, and then the rays coming from different directions for further reflections on the workpiece 8th incident.

As well how the corners can the faces, deviating from plane surfaces, as spherical or aspherical surfaces be educated.

The modified surface shape can be done either by a corresponding surface shape of the mirror surface on the faces or the corners or by firmly on the peripheral mirror 5 attached additional mirror elements 14 as in the 5 and 6 shown.

As in 5 shown, the workpiece can 8th with its workpiece axis 11 also parallel to the peripheral mirror system axis 9 be arranged.

This in 6 shown fourth embodiment of a peripheral mirror 5 is formed by a mirror with an octagonal cross-section.

Here comes the incident beam 3 , represented by five rays, first on a corner which is beam splitting. An additional mirror element 14 , which also divides the beam, but also interchanges the resulting partial beams in their direction of rotation, is shown.

Instead of a divergent beam 3 In contrast to all embodiments described above, a quasi-axis-parallel beam also in the XY plane 3 in the peripheral mirror 5 coupled.

In the embodiments described above, the beam becomes 3 so in the peripheral mirror 5 coupled to the optical axis 15 the peripheral mirror system axis 9 does not intersect by skewing to the perimeter mirror system axis 9 runs.

The ray bundle 3 However, according to the following two embodiments, it can also be coupled in and deflected such that the optical axis 15 with the peripheral mirror system axis 9 does not coincide by adding an additional mirror element 14 in the circumferential mirror 5 is arranged so that a first reflection takes place on it.

Also at the in 7 shown fifth embodiment, a quasi-axis-parallel in the XY plane beam 3 in the peripheral mirror 5 be coupled, which also has an octagonal cross-section, but with different edge lengths of the faces.

An additional mirror element 14 , here a rotating polygon mirror, ensures that the beam of light 3 , here represented by two marginal rays, is divided into two partial beams and this in a constantly changing deflection angle to different first partial surfaces of the peripheral mirror 5 incident. This has the beam 3 in contrast to all previous embodiments, a constantly changing course, until it is on the workpiece 8th , which by way of example has an elliptical cross section, impinges on a constantly changing location.

8th shows a sixth embodiment, in which also within the peripheral mirror 5 an additional mirror element 14 , here an angle mirror, is arranged.

Again, there is a first beam splitting of the beam 3 in partial beams, before this for the first time on a partial surface of the peripheral mirror 5 hit, ie before a first reflection on the peripheral mirror 5 , The partial beams propagate here mirror-symmetrically, in the opposite direction around the workpiece 8th from and meet several reflections on the workpiece 8th , The workpiece 8th has here for example a 5-corner with the same edge lengths as a cross section.

All the above embodiments have in common that a workpiece 8th through the impinging beams 3 completely with the radiation energy coming from a radiation source, in particular a laser 1 , is applied for a predetermined period of time.

However, a device according to the invention is not limited to a single radiation source and also not to a peripheral mirror 5 with perpendicular to the peripheral mirror system axis 9 standing surface normals 12 What should be shown in a seventh and eighth embodiment.

A seventh embodiment shown in FIG 9 , includes two lasers 1 each with upstream beam shaping optics 2 . 4 and in each case a jet entry opening 6 , This will, preferably at the same time, two beams 3 in the peripheral mirror 5 coupled. They can have the same beam geometry and at the same inclination angle β in the peripheral mirror 5 coupled, bringing the entry of the radiant energy into the workpiece 8th is doubled.

The beam shaping optics 2 . 4 but can also be interpreted differently, so that z. B. the width of the two beams 3 about the YZ-level differs to z. B. the workpiece 8th over a given workspace 10 harden by irradiation and at the same time within a much smaller work area 10 to separate.

The two beams 3 can also be at different heights in the perimeter 5 be coupled to z. B. when passing an upper work area 10 a first processing and when passing a lower work area 10 a second machining on the circumference of the workpiece 8th make.

In the illustrated embodiment are also additional, on the peripheral mirror 5 attached mirror elements 14 shown.

One of the two additional mirror elements 14 has a convexly curved mirror surface which detects the divergence of the incident beam 3 increased, while the other additional mirror element 14 consists of two flat faces that enclose an obtuse angle with each other, so that, while maintaining the divergence angle, the beam 3 in two Teilstrahlbün del is split.

The additional mirror elements 14 boundaries with concave transitions to the mirror surface of the peripheral mirror 5 which has a positive effect on the reflection.

An eighth embodiment shown in FIG 10 , differs from the aforementioned embodiments, in which the surface normals 12 of the peripheral mirror 5 at each point of the mirror surface perpendicular to the perimeter mirror system axis 9 stand, in that the surface normals 12 an equal angle less than 90 ° with the perimeter mirror system axis 9 lock in. The circumference mirror 5 can z. B. be a truncated pyramid or a truncated cone.

Depending on the angle, the beam becomes 3 in the direction of the peripheral mirror system axis 9 and thus the workpiece axis 11 distracted. This will be the workspace 10 increased.

Such a solution also has the advantage that a bundle of rays 3 not secured several times in the same places of the peripheral mirror 5 is reflected, resulting in lower thermal stress on the peripheral mirror 5 means.

With a ninth embodiment, shown in FIG 11 , should be pointed out that even only a partial circumferential machining of a workpiece 8th is possible.

The beam parameters of the beam 3 and the cross section of the peripheral mirror 5 and its dimension in conjunction with an additional mirror element 14 was chosen so that the beam 3 after beam splitting and double reflection completely on one side of a workpiece 8th , here a band-shaped strand of material, impinges.

A tenth embodiment is based on the 12 and the 13 be explained.

For a circumference mirror 5 formed by a cylindrical mirror with a 5-corner as a cross section, with edge lengths of 72.75 mm and a reflectance of 99.8%, the resulting energy distribution at the periphery of a workpiece 8th calculated with ten thousand rays at a threshold of 5%.

In 12 For this purpose, the beam path has been shown, with only ten beams of the beam in the illustration 3 are shown to ensure even a visual resolution.

13 shows in a diagram the number of impinging rays of the beam 3 which is equivalent to a distribution of the radiation energy caused by the impact of the radiation beams 3 on the workpiece 8th , distributed over its scope, was introduced into this.

The workpiece 8th is a material strand with a degree of absorption of 99.8% and a diameter of 25 mm, resulting in a circumference for the workpiece 8th of about 78.5 mm.

One in the perimeter mirror 5 coupled beam 3 has a half opening angle α of 6.4 ° and is in the jet inlet opening 6 bundled in a focus line.

looks If one looks at the illustrated curve, one recognizes circumferential sections, z. In the range of 43-65 mm, where the curve remains within a relatively narrow tolerance band. But it also recognizes peripheral sections with strong curve rashes, such as they do not satisfy a homogeneous circumferential processing.

Already a beam splitting before the first reflection in the peripheral mirror 5 would lead to an overlay with the mirror-inverted curve at half the number of beams and thus to a significant homogenization of the energy input to the workpiece 8th to lead.

For the machining target of completely cutting the workpiece 8th However, a distribution shown here may well be sufficient. On the other hand, for defined ablation over the circumference, measures must be taken to influence the course of the beams so that the distribution curve remains within an appropriate tolerance band over the entire circumference.

A more uniform distribution is achieved with an increase in the size ratio between the workpiece 8th and the peripheral mirror 5 and by the extensively explained in the embodiments measures for shaping and division of the beam 3 ,

Also, a homogenization can be easily achieved by the workpiece 8th during machining around its workpiece axis 11 is turned.

As already stated, the workpiece 8th and the device remain at rest during processing, or be in relative motion with each other. The relative rest position to each other can be achieved by the through the processing chamber 13 workpiece guided at a constant speed 8th for the time of Processing is stopped or advantageous by the optical system the workpiece 8th is tracked. Thus, the exposure time of the laser radiation can be increased.

All the aforementioned embodiments show that the method and the device, in particular depending on the cross section of the workpiece 8th and the processing target can advantageously be carried out differently. The person skilled in the art is given a large number of suggestions in order to arrive at an optimum result via this selection.

1

laser

2

first Beam shaping optics

3

ray beam

3.1-3.n

excellent Rays of the beam

3.1 ^m -3.n ^m

excellent Rays of the beam after mth reflection

4

second Beam shaping optics

5

extensive mirror

6

Beam entrance opening

7

Through opening

8th

workpiece

9

Extensive mirror system axis

10

Workspace

11

Workpiece axis

12

surface normal

13

processing chamber

14

additional mirror element

15

optical axis

α

half opening angle

β

tilt angle

R _SP

radius of curvature

R _i

limit radius

R _w

Workpiece radius

Claims (29)

Device for the circumferential machining of a workpiece ( 8th ), with an optical system having an optical axis ( 15 ) and to which a laser ( 1 ), which is a bundle of rays ( 3 ) along the optical axis ( 15 ) and a peripheral mirror ( 5 ), with a peripheral mirror system axis ( 9 ), around the workpiece to be machined ( 8th ), which has a workpiece axis ( 11 ) is arranged so that the peripheral mirror system axis ( 9 ) and the workpiece axis ( 11 ) are aligned in the same direction, characterized in that the peripheral mirror ( 5 ) at the periphery of a jet inlet opening ( 6 ), to which the optical system is arranged so that the radiation beam ( 3 ) with the optical axis ( 15 ) perpendicular to the peripheral mirror system axis ( 9 ) in the peripheral mirror ( 5 ) is coupled and after multiple reflection on the peripheral mirror ( 5 ) on the workpiece ( 8th ). Device according to claim 1, characterized in that the peripheral mirror ( 5 ) from a processing chamber ( 13 ), which likewise has a jet entry opening ( 6 ) and two passage openings ( 7 ), through which the workpiece to be machined ( 8th ) in the direction of its workpiece axis ( 11 ) through the processing chamber ( 13 ) is guided. Device according to Claim 1, characterized in that the optical system has a first beam-shaping optical system ( 2 ) for the change in diameter and parallelization of the laser ( 1 ) emitted beam ( 3 ). Device according to Claim 1 or 3, characterized in that the optical system has a second beam-shaping optical system ( 4 ), for focusing the beam ( 3 ) in the XY plane, which is a plane perpendicular to that through the optical axis ( 15 ) and the peripheral mirror system axis ( 9 ) defined YZ-level. Apparatus according to claim 4, characterized in that the second beam-shaping optical system ( 4 ) is designed such that a forming focal line in a beam entry opening ( 6 ) lies. Device according to claim 1, characterized in that the peripheral mirror ( 5 ) has the shape of a hollow body whose inner lateral surface forms a mirror surface whose surface normal ( 12 ) at each point of the mirror surface perpendicular to the perimeter mirror system axis ( 9 ) stand. Device according to claim 1, characterized in that the peripheral mirror ( 5 ) has the shape of a hollow body whose inner lateral surface forms a mirror surface whose surface normal ( 12 ) at each point of the mirror surface an angle which is less than 90 °, with the peripheral mirror system axis ( 9 ) lock in. Apparatus according to claim 6 or 7, characterized in that the mirror surface may be composed of a plurality of sub-surfaces, the corners include each other and their number, geometry and arrangement to each other for the cross section of the peripheral mirror ( 5 ) is determinative. Device according to claim 6 or 7, characterized that the mirror surface a circular cylindrical area is. Apparatus according to claim 8, characterized in that through the faces polygons with the same edge lengths and the same internal angles are formed. Apparatus according to claim 1, characterized in that in the interior of the peripheral mirror ( 5 ) at least one additional mirror element ( 14 ) is available. Apparatus according to claim 11, characterized in that the additional mirror element ( 14 ) is a rotating polygon mirror. Device according to claim 1, characterized in that on the peripheral mirror ( 5 ) at least one additional mirror element ( 14 ) is arranged. Apparatus according to claim 1, characterized in that the workpiece axis ( 11 ) in the circumferential mirror system axis ( 9 ) is arranged. Device according to claim 8, characterized in that that at least one corner or a partial surface is formed as a spherical or aspherical surface is. Apparatus according to claim 1, characterized in that an additional jet entry opening ( 6 ) and a second optical system are provided to two beams ( 3 ) in the peripheral mirror ( 5 ). Apparatus according to claim 16, characterized in that the second optical system comprises a laser ( 1 ) having a radiation beam ( 3 ) emitted at a different wavelength than the laser ( 1 ) of the first optical system. Device according to claim 1, characterized in that at least one movement device is provided which is capable of a relative movement between the optical system, the peripheral mirror ( 5 ) and the workpiece ( 8th ) to create. Device according to Claim 1, characterized in that at least one movement device is provided which is suitable for the optical system, the peripheral mirror ( 5 ) and the workpiece ( 8th ) together in the direction of the workpiece axis ( 11 ) to move. Method for the circumferential machining of a workpiece ( 8th ) by means of laser ( 1 ), in which a peripheral mirror ( 5 ) with a circumferential mirror system axis ( 9 ) and a workpiece ( 8th ), with a workpiece axis ( 11 ), so in the peripheral mirror ( 5 ) that the peripheral mirror system axis ( 9 ) and the workpiece axis ( 11 ) in one direction, characterized in that, for a predetermined processing time, one of the laser ( 1 ) emitted beam ( 3 ) along an optical axis ( 15 ) perpendicular to the peripheral mirror system axis ( 9 ) in the peripheral mirror ( 5 ) is coupled in and on the mirror surface is reflected several times until it is on the workpiece ( 8th ). Method according to claim 20, characterized in that the radiation beam ( 3 ) before it enters the peripheral mirror ( 5 ) is parallelized. Method according to claim 20 or 21, characterized in that the beam ( 3 ) before it enters the peripheral mirror ( 5 ) in a direction perpendicular to the peripheral mirror system axis ( 9 ) is focused. Method according to claim 20, characterized in that the workpiece ( 8th ) during the machining time along its workpiece axis ( 11 ) relative to the peripheral mirror system axis ( 9 ) is moved and / or about its workpiece axis ( 11 ) is rotated. A method according to claim 20, characterized in that the optical system during the processing time in the direction of the workpiece axis ( 11 ) is moved. A method according to claim 20, characterized in that the optical system and the peripheral mirror ( 5 ) during the machining time in the direction of the workpiece axis ( 11 ) are moved. Method according to claim 20, characterized in that the optical system, the peripheral mirror ( 5 ) and the workpiece ( 8th ) during the machining time in the direction of the workpiece axis ( 11 ) are moved. Method according to claim 20, characterized in that the radiation beam ( 3 ) is divided into two partial beams before a first reflection. Method according to claim 20, characterized in that more than one beam ( 3 ) in the peripheral mirror ( 5 ) are coupled. Method according to claim 28, characterized in that the radiation beams ( 3 ) have different wavelengths.